Sniffing and Spoofing are security threats that target the lower layers of the networking infrastructure supporting applications that use the Internet. Users do not interact directly with these lower layers and are typically completely unaware that they exist. Without a deliberate consideration of these threats, it is impossible to build effective security into the higher levels. If the network packets are not encrypted, the data within the network packet can be read using a sniffer.
Sniffing data from the network leads to loss of privacy of several kinds of information that should be private for a computer network to be secure. These kinds of information include the following: